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Nakanishi A.,Aichi Prefectural Forestry Research Institute | Yoshimaru H.,Japan Forestry and Forest Products Research Institute | Tomaru N.,Nagoya University | Miura M.,Japan Forestry and Forest Products Research Institute | And 2 more authors.
Tree Genetics and Genomes | Year: 2015

Highly frequent pollination at short distances combined with spatial genetic structure (SGS) among reproductive individuals, as observed in populations of many forest tree species, may lead to highly frequent pollinations between genetically related individuals located close to each other. This could increase frequencies of biparental inbreeding and strengthen the degree of SGS across generations. However, the degree of SGS observed in forest tree populations is not usually strong, suggesting that such processes are restricted by other factors, which may include inbreeding depression. To test this hypothesis, we examined inbreeding depression in Castanopsis sieboldii saplings in a population known to have significant SGS and high frequencies of short-distance pollination. We determined genotypes at eight microsatellite loci of 125 adult trees and 899 saplings in a 4-ha plot. The neighborhood model approach, assuming an exponential power function, showed highly frequent pollination at short distance among parents of saplings. SGS was significantly stronger among saplings than among adults. The average value of Fis (individual inbreeding coefficient based on kinship coefficients between genes within individuals) was also significantly higher among saplings than among adults. Furthermore, average values for saplings were relatively high (0.036–0.052) in 30–50 to 90–110 cm height classes and rapidly decreased to 0.006 for the ≥110-cm class. Analysis of covariance, taking into account the canopy state, showed that inbreeding depression had a significant negative effect on the saplings’ height. Thus, the level of inbreeding in saplings decreased with size classes increasing, probably due to pronounced inbreeding depression resulting in mortality or reduced growth of inbred saplings, and hence, the inbreeding depression may prevent increasing of the level of inbreeding and the degree of SGS in subsequent generations. © 2015, Springer-Verlag Berlin Heidelberg.

Agathokleous E.,Hokkaido University | Watanabe M.,Tokyo University of Agriculture and Technology | Eguchi N.,Hokkaido University | Eguchi N.,Aichi Prefectural Forestry Research Institute | And 3 more authors.
Water, Air, and Soil Pollution | Year: 2016

We examined the root production of a set of Fagus crenata (Siebold’s beech) saplings grown in an infertile immature volcanic ash soil (VA) and another set in a fertile brown forest soil (BF) with both sets exposed to elevated CO2. After the saplings had been exposed to ambient (370–390 μmol mol−1) or elevated (500 μmol mol−1) CO2, during the daytime, for 11 growing seasons, the root systems were excavated. Elevated CO2 boosted the total root production of saplings grown in VA and abolished the negative effect of VA under ambient CO2, but there was no significant effect of elevated CO2 on saplings grown in BF. These results indicate the projected elevated CO2 concentrations may have a different impact in regions with different soil fertility while in regions with VA, a higher net primary production is expected. In addition, we observed large elevated CO2-induced fine-root production and extensive foraging strategy of saplings in both soils, a phenomenon that may partly (a) adjust the biogeochemical cycles of ecosystems, (b) form their response to global change, and (c) increase the size and/or biodiversity of soil fauna. We recommend that future researches consider testing a soil with a higher degree of infertility than the one we tested. © 2016, Springer International Publishing Switzerland.

Nakashima H.,Aichi Prefectural Forestry Research Institute | Eguchi N.,Aichi Prefectural Forestry Research Institute | Uesugi T.,Mie University | Yamashita N.,Aichi Prefectural Forestry Research Institute | Matsuda Y.,Mie University
Trees - Structure and Function | Year: 2015

Key message: Ectomycorrhizal composition and associated fungi affect the intra-specific ability of resistant black pines for physiological adaptation.Abstract: Since Japanese black pine (Pinus thunbergii Parl.) forests have been widely devastated by pine wilt disease, several kinds of resistant black pines have been developed. Although all of the resistant black pines are the same species, these resistant trees show different physiological characteristics. We investigated the survival rates and growth rates, as well as ectomycorrhizal composition and associated fungi, on four kinds of Japanese black pine seedlings (three pine wilt-resistant and one non-resistant), and elucidated the factors affecting the various physiological characteristics. We found that the abundance of ectomycorrhizal types differed even though seedlings were grown sympatrically in the same areas for about 2 years. The seedlings that had plentiful white ectomycorrhizae showed the highest survival and growth rates regardless of the variety of black pine. Sequence similarities of the white ectomycorrhizae in the rDNA ITS region were best matched with members of Astraeus sp., Atheliaceae, Boletaceae and Thelephoraceae. Our findings indicate that intra-specific physiological adaptation might be affected by ectomycorrhizal composition or by the specific ectomycorrhizal species. © 2015 Springer-Verlag Berlin Heidelberg

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